Ooh yes it looks scary! Hey, an ornament is the perfect project for a new technique like this. If you hate doing it, it will only take a short time to finish, and you can refuse ever to look at Fair Isle again. Or, worst case, you don’t do it at all, and you’ve only purchased a small amount of wool to find a new use for.
I thought I’d never do Fair Isle because it looks tricky and I had never seen a Fair Isle item that I wanted. I just think most Fair Isle objects are hideous (sorry to you FI fans!). Then I saw Eunny’s mittens and armwarmers and was converted. I’m going to learn colourwork. Soon. Truly. Anyway Eunny has some tips for colourwork beginners. Knitty has an article on it too. As far as I know a big problem is that a colour carried behind, if pulled too tight, will make the work pucker, the main tip I’ve seen suggested to stop this is to stretch your stitches far apart on the needle (apparently easier on wooden/bamboo needles) and pull the wool very loosely.
I’ve also seen a fingertip ring (like a thimble) that has loops to hold two strands of different colours, this may be very useful. Otherwise, I think being able to knit Continental may be helpful, so you can carry the two colours on different fingers.
But as far as I can tell, none of these is absolutely necessary. Good luck and please let us know how you find it!